Clinical Studies have been undertaken to identify new agents or combinations of agents that may have activity in patients with relapsed acute leukemia. The following studies have been completed AMSA (20% CR rate in ANLL ) and AZQ (dose finding only). The following projects are in progress: Ara-C + TdR, DHAD, nitrous oxide, whole body hyperthermia and AMSA vs. Poly I G-L-Lysine (the later study for maintenance therapy in reucurrent leukemia only).